1. Field of Invention
The present invention relates, in general, to a transmission clutch, and more particularly, to a method of accurately estimating the torque of a transmission clutch that is transmitted through slip in a dry clutch of a dual clutch transmission (DCT).
2. Description of Related Art
Recently, the development of dual clutch transmissions (DCTs) is actively underway since DCTs can realize not only the driving convenience of automatic transmissions but also high fuel efficiency and high power efficiency of manual transmissions. DCTs are a type of semi-automatic transmissions based on a manual transmission system, in which two torque transmission shafts are provided, and a clutch is automatically controlled without a torque converter. DCTs have an advantage of high fuel efficiency. However, in a DCT system using a dry clutch, two working parts of the clutch are directly engaged without a torque converter, and thus the start and transmission performance of a vehicle is dependent on clutch control performance. Furthermore, since it is impossible to directly measure transmission torque that occurs at the friction surface of a disk, it is important to obtain a measurement of the transmission torque of the clutch.
Among conventional methods of estimating clutch torque, there is a method of utilizing the observer theory of control engineering. This is the method of calculating transmission torque that occurs at the slipping of a clutch disk. An engine torque outputted from an electronic control unit (ECU) is based on a data obtained through repeated tests in a static state. However, a point of time when clutch torque information is required always corresponds to a transient state (creep, departure, etc.) of the engine, and thus there is a difference between the engine torque from the ECU and an actual torque. Therefore, an estimated clutch torque obtained based on the uncertain engine torque also has an error, which is problematic.
The present invention is directed to provide a method of estimating an accurate clutch torque by adjusting an error in an uncertain engine torque model.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.